School of Chemical and Biological Engineering, Institute of Chemical Processes, College of Engineering, Seoul National University, Seoul 08826, Korea.
ACS Appl Bio Mater. 2021 Feb 15;4(2):1863-1875. doi: 10.1021/acsabm.0c01539. Epub 2021 Jan 25.
Development of sensing elements for controllable soft materials is crucial to improve their responsiveness toward remotely provided external stimuli. Magnetic nanoparticles (MNPs) and gold nanoparticles (AuNPs) have been coassembled into a flexible free-floating 2D film to produce a shape deformable mobile structure in the presence of magnetic field and light irradiation by employing a self-assembly protein of α-synuclein (αS). αS was demonstrated to be essential for the preparation of a multisensory system because the intrinsically disordered protein led to a complete dispersion of MNPs to an average size of 10 nm in aqueous solution, pH-dependent closely packed single layer adsorption of αS-MNPs, and α-helix-mediated free-floating MNP monolayer film formation upon dissolving the underlying polycarbonate substrate with chloroform. As AuNPs were incorporated into the assorted hybrid film in the presence of MNPs, however, the β-sheet component became prominent. By placing the assorted film between a spin-coated thin layer of thermoresponsive P(AAc--NIPAAm) hydrogel comprising acrylic acid and -isopropylacrylamide and a passive layer of silicone elastomer, the resulting triply structure exhibited not only magnet-induced locomotion but also shape deformation due to asymmetric contraction of the sandwiching two layers caused by the heat generated by AuNPs upon near IR irradiation. In fact, two adjoining planar layers of another triply structure were shown to form a three-dimensional lotus flower with the light. This multisensory system is suggested to be further functionalized by modifying the αS molecules and incorporating additional nanoparticles to react to diverse stimuli, which would make the system be utilized in the areas of not only soft robotics but also foldable electronics, high-performance sensors/actuators, and medical/wearable applications.
发展可控制软材料的传感元件对于提高其对外界远程提供的刺激的响应能力至关重要。通过使用α-突触核蛋白（αS）的自组装蛋白，将磁性纳米粒子（MNPs）和金纳米粒子（AuNPs）共组装成柔性游离的 2D 薄膜，在磁场和光照射的存在下产生可变形的移动结构。αS 被证明是制备多感觉系统所必需的，因为这种无序的蛋白质导致 MNPs 在水溶液中完全分散到平均 10nm 的尺寸，在 pH 依赖性的紧密单层吸附中，αS-MNPs 被紧密排列，并且在溶解底层聚碳酸酯基底时，通过形成α-螺旋介导的游离 MNPs 单层薄膜。然而，当 AuNPs 与 MNPs 一起掺入到混合的杂化薄膜中时，β-折叠结构变得明显。通过将杂化膜放置在涂覆有热响应性 P(AAc-NIPAAm)水凝胶的旋涂薄层之间，该水凝胶包含丙烯酸和异丙基丙烯酰胺，以及被动层的硅酮弹性体，所得的三层结构不仅表现出磁诱导运动，而且由于 AuNPs 在近红外照射下产生的热引起的夹在两层之间的不对称收缩而导致形状变形。实际上，另一个三层结构的两个相邻平面层在光的作用下形成了三维的莲花。这个多感觉系统可以通过修饰αS 分子和掺入额外的纳米粒子来进一步功能化，以对不同的刺激做出反应，这将使该系统不仅在软机器人领域，而且在可折叠电子、高性能传感器/执行器以及医疗/可穿戴应用领域得到应用。
